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Shape-shifting hormones keep hearts healthy

WOMEN who opt for hormone treatment after the menopause are less likely
to suffer from heart disease because the hormones alter the shape of the body,
giving them younger—and healthier—figures.

At the European Congress on Obesity in Barcelona this week, an Australian
endocrinologist produced striking evidence that hormone replacement therapy
(HRT), the biggest known protective factor against coronary heart disease in
postmenopausal women, saves lives by shifting fat from around the waist to other
parts of the body where it does less harm.

“Our findings suggest that part of the reduction in heart disease risk in
women who use oestrogen replacement after menopause may be explained by its
association with lower amounts of central fat,” says Katherine Samaras of the
Garvan Institute of Medical Research in Sydney.

Samaras studied 560 postmenopausal women at the Twin Research Unit of St
Thomas’s Hospital, London. She compared the body fat of women on HRT with those
who were not. The women taking hormones had less body fat overall but, more
importantly, they had 9 per cent less fat around their abdomens.

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Fat around the torso is a known risk factor for heart disease: “apple-shaped”
women whose fat accumulates around the waist have a higher risk of heart
disease, diabetes and high blood pressure than the classic “pear-shaped” woman,
whose fat tends to gather around the buttocks and thighs.

Mike Lean, professor of human nutrition at the University of Glasgow, says
Samaras’s findings are “very interesting”. “Women on HRT may be returning to the
premenopause shape, which is pear-shaped,” he says.

He suggests that doctors who are worried about a patient’s weight might be
better off considering the extent of their waistline rather than the more usual
measure of obesity, the body mass index. BMI is calculated by dividing weight in
kilograms by the square of the height in metres. “Many people find it hard to
calculate,” he says. “So why not use the waist? It correlates better than, or at
least as well as, anything else with breathlessness, diabetes and bad
lipids.”

He advocates a simple waist measurement scale for gauging a patient’s risk of
heart problems. Women should start to watch their waist when it reaches 80
centimetres (31.5 inches). Once it reaches 88 cm (34.6 inches) they need to act
urgently, he says. The lower and upper figures for men are 94 cm (37 inches) and
102 cm (40.2 inches).

“There’s no question that high waist fat is linked to coronary risk,” says
Kay-Tee Khaw, professor of clinical gerontology at Addenbrooke’s Hospital in
Cambridge. Khaw says that lipids from fat stores around the waist are mobilised
and move into the bloodstream more readily than lipids from other parts of the
body, leading to higher levels of low-density lipids. This is the form of
cholesterol that is thought to leave deposits, causing narrowing of the
arteries.

The protective effect of HRT was firmly established in the 1980s by the
long-running Nurses’ Health Study in the US. This showed that HRT halves the
risk of a major heart attack in postmenopausal women.

However, Khaw points out that the study was not randomised and so the sharp
reduction in risk might have been because the nurses in this group were better
informed about healthy lifestyles and opted for HRT as a result. “The 50 per
cent protective effect may in reality be anything between that and 10 per cent,”
she says.

In Britain last week, the Medical Research Council decided to contribute
£21 million to an international study to establish once and for all the
risks and benefits of HRT. In the British part of the study, 18 000 women will
take HRT for 10 years and be followed up for another 10 years. A further 16 000
women in other countries will also take part. “We hope this will be definitive,”
says a spokesman for the council.

The MRC hopes the results will persuade women that the benefits of
HRT—stronger bones and healthier hearts—outweigh the slightly
increased risk of breast and endometrial cancers.